Documentation exclusions?

There are a couple things that don't appear in the docs but are referenced
elsewhere. In both cases I am wondering whether the docs have
fallen out of sync with the code base, whether these features have
been deprecated or ??

$app->contentType(string $type) is mentioned in
the
API docs, but I can't find a reference to it in the docs.

Class controllers are mentioned in the 2.4.0 release
notes, but again I can't find a reference to them in the
docs.

The documentation has fallen out of sync, some of these new
features are not documented and because we are busy trying to get
Slim 3 out the door, this sometime become an oversight with the
current doc, but will try and get this rectified soon or you can
also send a PR and get it merged in. The documentation is on Github
also.